The Cooperative Distributed Interactive Atmospheric Catalog System (CODIAC) offers on-line access to research and operational atmospheric science data sets distributed across geographically dispersed data centers. The system provides the means to identify data sets of interest, the facilities to view associated metadata, and the ability to automatically obtain data and metadata via Internet file transfer or removable media. The data system currently provides access to carefully quality-controlled data sets from research campaigns such as the U.S. Weather Research Program's STORM-FEST campaign, GEWEX/GCIP Initial Data set - 1 (GIDS-1), and the Central Equatorial Pacific Experiment (CEPEX). It also provides access to numerous operational data sets archived at NCDC via the OASIS node. Contact: User assistance is provided by submitting email to codiac@ucar.edu